fNIRS as a biomarker for individuals with subjective memory complaints and MCI.

INTRODUCTION: Identifying individuals at risk of developing dementia is crucial for early intervention. Mild cognitive impairment (MCI) and subjective memory complaints (SMCs) are considered its preceding stages. This study aimed to assess the utility of functional near-infrared spectroscopy (fNIRS) in identifying individuals with MCI and SMC. METHODS: One hundred fifty-one participants were categorized into normal cognition (NC); amnestic MCI (aMCI); non-amnestic MCI (naMCI); and mild, moderate, and severe SMC groups. Task-related prefrontal hemodynamics were measured using fNIRS during a visual memory span task. RESULTS: Results showed significantly lower oxyhemoglobin (HbO) levels in aMCI, but not in naMCI, compared to the NC. In addition, severe SMC had lower HbO levels than the NC, mild, and moderate SMC. Receiver operating characteristic analysis demonstrated 69.23% and 69.70% accuracy in differentiating aMCI and severe SMC from NC, respectively. DISCUSSION: FNIRS may serve as a potential non-invasive biomarker for early detection of dementia. HIGHLIGHTS: Only amnestic mild cognitive impairment (aMCI), but not non-amnestic MCI, showed lower oxyhemoglobin (HbO) than normal individuals. Reduced HbO was observed in those with severe subjective memory complaints (SMCs) compared to normal cognition (NC), mild, and moderate SMCs. Functional near-infrared spectroscopy measures were associated with performance in memory assessments. Prefrontal hemodynamics could distinguish aMCI and severe SMC from NC.

Dose Response of Transcranial Photobiomodulation on Cognitive Efficiency in Healthy Older Adults: A Task-Related Functional Near-Infrared Spectroscopy Study.

Background: Alzheimer's disease has become increasingly prevalent among the older population, leading to significant social and economic burdens. Transcranial photobiomodulation (tPBM) has shown promise as a cognitive intervention for enhancing cognitive efficiency in healthy older adults, and individuals with mild cognitive impairment and Alzheimer's disease. However, determining the optimal tPBM dosage is crucial for ensuring effective and efficient intervention. Objective: This study aimed to compare the effects of different dosages in a single tPBM session on cognitive efficiency in healthy older adults. Methods: In this randomized controlled trial, 88 healthy older participants were assigned to either a single dose (irradiance = 30 mW/cm2, fluence = 10.8 J/cm2; n = 44) or a double dose (irradiance = 30 mW/cm2, fluence = 21.6 J/cm2; n = 44) tPBM session. Cognitive efficiency was assessed using functional near-infrared spectroscopy during a visual working memory span task. Results: The single dose group exhibited significantly greater cognitive efficiency enhancement, indicated by a more pronounced reduction in oxygenated hemoglobin during a challenging task level (span level 9) (p = 0.021, d = 0.50), and better working memory task performance (p = 0.045, d = 0.31). Furthermore, participants with better visuospatial abilities demonstrated greater improvement after a single dose (r = -0.42, p = 0.004). In contrast, participants with varying cognitive function did not exhibit additional benefits from a double dose (r = -0.22-0.15, p = 0.16-0.95). Conclusions: These findings suggest that higher tPBM dosages may not necessarily result in superior cognitive improvement in older adults.

Chanwuyi Lifestyle Medicine Program Improves Memory and Executive Functions of Older Adults With Mild Cognitive Impairment.

The Chanwuyi Lifestyle Medicine Program (CLMP) was found to enhance the memory and executive functions of older adults with or without subjective memory complaints. The present study investigated whether similar beneficial effects can be extended to mild cognitive impairment (MCI). Twenty-four older adults with MCI were randomly assigned to receive the CLMP (the experimental group) or strategic memory training (SMT; the active control group) for 10 weeks. They were assessed by neuropsychological tests at baseline and post-intervention. Older adults showed similar visual and verbal memory improvements after receiving the CLMP and SMT. Yet, only those who received the CLMP showed distinct improvements in planning/organization, working memory, and attention in terms of accuracy, with greater cognitive gains associated with older age and lower levels of education and baseline cognitive functions. This study provides preliminary evidence for the effects of the CLMP on improving memory, attention, and executive functions in MCI.